Gear-cutting machine.



I. E. MOORAGKEN. GEAR CUTTING MACHINE.

APPLOATION FILED 0GT.2, 1912.

Patented Fb.3,1914.

2 anus-min 1.

FIG. 9

FIG.1

mvsm'on WITNESSES W M g I. .E. MdCRACKEN.

GEAR CUTTING MACHINE. APPLIOIATION FILED 00122, 1912.

Pater used Feb. 3, 1914.

2 SHEETS-SHEET 2.

INVENTOR ISAAC E. MGCRACKEN, OF PITTSBURGH. PENNSYLVANIA.

GEABFCUTTING MACHIN E.

Specification of Letters Patent.

Patented Feb. 3, 191%.

Application filed October 2, 1912. Serial No. 723,578.

To all w/wm it may concern I Be it known that I, IsAAo E. MoCnAcxEN, aresident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in(ieardlutting Machines, of' which the following is a specification.

This invention relates to a machine for cutting gears or pinions. andparticularly what are known as herring bone gears or pinions.

The object of the invention is'to provide a new and improved machine forforming a special type of herring bone gear having continuous teethacross the full width of the gear, and which machine cuts or forms saidteeth for their full length by a continuous cutting operation, therebyproducing a gear having full strength along its median plane.

The invention comprises the construction and arrangements of partshereinafter described and claimed.

In the drawings Figure 1 represents a plan view of a machine constructedaccording to my invention; Fig. 2 is a broken out side elevationthereof, parts being shown in section: Fig. 3 is a detail section on theline 33. Fig. 2. and showing the indexing mechanism; Figs. 4t and 5 arerespectively plan and side elevations of the tool spindle and toolcarried thereby; Fig. 6 is a detail view showing the indexing worm; Fig.7 is a detail View of a clutch member and its cmitrolling mechanism;Fig. 8 is a detail view of a latch; Fig. 9 is a plan of a gear formed onthe present machine; and Figs. 10 and 11 are diagrammatic viewsillustrating the teeth being cut.

The machine shown in the drawingscomprises a suitable bed or table 1, atone end of which are erected standards 2 supporting a double carriage 3in which is rotatable a horizontally disposed work holding arbor 4. Themembers 3 of carriage 3 are provided with threaded nuts 5 in which workinterconnected screws 6 operated by interineshing gears 7 fromcontrolling shaft 8 for adjusting the carriage and work holding arbor 4tvertically along the usual ways on the standards 2. The bed or table 1is provided with the usual longitudinal ways 10, along which travels atool carriage 11 having a standard 12 at the forward end thereof inwhich is journaled a tool holding arbor 13 having its axis disposedlongitudiof the standard 12.

nally of the bed or table and transverse to I the axis of the workholding arbor 1.

The tool carrying spindle 13 rotates in a su table bearing 14 instandard 12 and its forward end projects through a face plate or block15 rigidly secured to the front Wall Spindle 13 at its forward end isprovided with a head 16 formed of two parallel transverse wings or arms17 between which is mounted a tool holder or carrier 18 which swings oroscillates on a pin 19 passing through said wings or arms. The axis ofthe pivot 19 passes through the longitudinal axis of the spindle 13 butat right angles thereto, so that the tool holder 18 swings in a planepassing through the axis of the tool spindle. Tool holder 18 is grooved,as at 20, to receive a transverse rib 21 on a tool or cutter 22 rigidlysecured to the tool holder by a suitable bolt 23 passed through anaperture in the tool. [001 holder 18 is provided with one or more slotsor apertures 24 so arranged that the tool 22 can be secured atdifl'erent distances from the axis of the tool spindle. The back of toolholder 18 is provided'with a cylindrical socket 25 having its axisnormal to the axis of spindle 13, and in which is mounted a ball orroller 26, a. portion of.

which projects through an opening 27 in the tool holder, and during thecourse of movement of the same around the axis of spindle 13 travelsover the cam surface 28 of an annular guide or former 30, rigidlysecured in an annular groove 29 in the front fare of the plate or block15. A yoke 31 is secured to and embraces the arms 17 of the tool head 16and forms an abutment for a mmpression spring 32, which tightly pressesthe tool holder 18 and the roller 26 carried thereby into contact withthe curved guide or former.

As indicated in Fig. 2, the cutting portion 33 of the tool is eccentricto the axis of spindle 13 and projects forwardly toward the cylindricalblank A to'be cut. To form a tooth on the blank, arbor 4 is adjustedvertically in standards 2 until its axis is substantially horizontallyin line with the axis of the tool spindle 13, although it may be eitherabove or below, and is shown as slightly above the same. A guide orformer 30 of the proper shape being secured in the groove 29 in theplate or block 15, the spindle 13 then rotated and the tool i carriage11 moved longitudinally oflthe bed 1 toward the work carrying arbor 4.As the spindle 13 rotates the eccentrically mounted tool 22 sweepsacross the face of the cylindrical blank in a curved path and in avertical plane, and at each complete rotation of spindle 13 makes onecut clear across the face of the blank. The tool also gradually cuts itsway deeper andi deeper into the work as the carriage l1 .isfedforwardly.

Since the surface of blank A is cylindrical and the tool. in sweepingacross the blank, rises and falls with relation to arbor 4, itis clearthat the cut would vary in depth if the tool were innnovably fixed onspindle 13. For this reason the tool holder 18 swings as described onthe pivot 19, and is moved more or'less toward the axis of arbor 4 bythe cam 30, thereby producing a uniform pitch line and uniform depth ofcut for the full length of the tooth. A separate cutting operation isrequired for each side of each tooth. When one side of a given toot-hhasbeen properly shaped the blank is then rotated or indexed one-space andthe same operation performed to form the same side of the next tooth,and so on completely around the blank.- After half of each tooth hasbeen formed in this manner the arbor 4 is then adjusted vertically for adistance equal to the thickness of the tooth across the pitch line tobring the other sides of the teeth.

into the proper position with relation to the path of movement of thecutting tool. The operation then proceeds as before until the othersides of all of the teeth have been successively formed, the finishedgear having the appearance of that illustrated in Fig. 9.

Any suitable mechanism may be provided for rotating the tool and movingthe tool carriage longitudinally on the bed. In the form shown alongitudinal driving shaft is located centrally in suitable bearingsunderneath the bed of the machine and carries loose and fast drivingpulleys 36, 36 at one end thereof. Tool carriage 11 is provided with adownwardly projecting bracket 37 carrying a bevel gear 38 therein, whichgear is splined on shaft 35 and meshes with a bevel gear 39 on avertical shaft 40iconnected to drive the tool spindle 13 by intermeshingbevel gears 41. Gear 38 travels along shaft as thdcarriage movesendwise. At its rear end shaft 35 is provided with a pair, of for-.

ward and reverse bevel gears 42 and 43 which both mesh with a bevel gear44 on a vertical shaft 45, which is connected by bevel gears 46 torotate a feed screw 47 connected to a nut 48 on the carriage 11. Gears42 and 43 are loose on the shaft 35 and-are driven thereby through aclutch member 49 connected to rotate with said shaft and having teeth toengage coiiperatin' clutch teeth on gear members 42 and 43. lutoh 49 isoperated by a lever 50 pivoted at 51 toa fixed portion of the bed andsuitably connected to a clutch operating rod 52 on which are adjustablymounted suitable tappets or stops 53, 53 arranged to be engaged by aproject ing arm or bracket 54 rigidly connected to the tool carriage 11.As the tool carriage 11 travels rearwardly, or away from the workcarrying. arbor, arm 54 strikes stop 53 and moves the rod 52 rearwardlyto throw the clutch member 49 into engagement with gear member 42 androtate feed screw '47 in a directionto feed the tool carriage forwardly.When the carriage reaches its for ward limit of movement, arm 54 strikes.stop 53 and throws the clutch 49 to its other position and reverses themovement of the tool carriage.

If desired, suitable means may also be provided for securing a quickthrow of the clutch 49 in both directions to thereby pre vent the clutchfrom assuming an inactive neutral position. In the form shown a V-shaped latch 55 is movably mounted upon the clutch lever 50 under theinfluence of a compression spring 56 and is arranged to engage a similarfixed latch or dog 57 on the bed. The inclined surfaces of the mem here55 and 57 are so arranged that the clu\tch. is stable only when in oneor the other of its extreme positions of movement and when moved alittle more than half way in either direction, spring 56 quickly throwsthe clutch the rest of the way to reverse the carriage. Preferably, thegears are so proportioned that the forward feed of the carriage is veryslow, so the depth of cut at one end of the tooth or gear will besubstantially the same as at the other end.

Any suitable means may be provided for indexing the work arbor 4 tobring suoces-* sive portions of the blank A into position to be operatedupon by the cutting tool. In the-form shown in the drawings shaft 35drives a transverse shaft 60 through intermeshing bevel gears .61. Shaft60 is connected to drive a. sleeve 60 thereon by a slipping frictionclutch, one member 62 of which is on the sleeve and isprovided with iinfluence of a compression spring 66. The

other member 64 is splined on shaft 60 and pressed into contact withmember 62 by a suitable spring 64*. Sleeve 60 at its outer end isprovided with a inion 67 which is arranged to-drive a shaft 68 locatedabove shaft 60 and parallel thereto,through the interposition of changegears 69 on a shaft 70 carried by an arm 71 swinging around the axis ofshaft 68. Shaft 68 drives a vertical shaft 72 through bevel gears 73,said shaft 72 being provided with a worm 74 which drives a worm gear 75fixed to the work carrying arbor 4.

While the-tool is cutting a tooth the dog on the controlling rod 65 isheld in engagement with the notch 63 in the friction member. 62 andprevents this member from rotating. The clutch members thereforenormally slip on eachother. lVhenever the carriage is; reversed andmoves rearwardly (r-away from the work carrying arbor, an arm 76 fixedto the carriage strikes a stop 77' adjustably mounted on the controllingrod 65 and moves dog 65 out of engagement with the socket 63 in thefriction mem ber 62. The two members of the friction clutch then rotateas one and the vertical shaft 72 is driven from the horizontal shaft 60through the gear 67, change gears 69 and shaft 68. After the stop 77 hasbeen forced rearwa-rdly the arm 54 contacts stop.

:33 and throws clutch all). The carriage 11 then starts forward uponanother stroke, at the same time releasing the stop 77 from contact withthe arm 76. The dog 65 is then forced yieldingly by spring 66 intocontact with the periphery of the slip member 62 which thereupon rotatesfor one complete revolution; When the notch 63 again comes around, dog65 enters thereinto and the clutch again slips. The gearing is, ofcourse, so proportioned .that the complete rotation of member 62 is.finished before the carriage advances far enough to move the tool intoengagement with the work. The rotation of member 62 in the mannerdescribed rotates the worm 74and worm gear 75 and indexes the blank Aone step. The amount of this movement-may be varied by changing therelation of the change gears 69 so that one complete revolution of shaft60 will rotate the worm 74 more or less as desired to suit differentsizes of gears. It will also observed that the indexing of the workcarrying arbor begins just before the tool carriage 11 has reached therear limit of its movement and is completed while the tool is wholly outof engagement with the work.

The machine described is operated in the following manner: A.suitableblank A is secured to the work carrying arbor 4 in suchposition that 'its .central or median plane. indicated by the dottedline B in Fig. 1, is in line with the axis of rotation 'of'the toolcarrying spindle 13. The arbor 4 is then adjusted vertically to theproper position and a tool 22 of the proper shape is secured in the toolholder. The machine is then started and the tool carriage '11 travelsforwardly toward the work carrying arbor-4 and at each revolution ofshaft 13 the roller '26 rides over the former or guide 30 and forces thetool forwardly into engagement with the blank. Preferably, the axis'ofthe tool spindle 13 is placed sub stantially in line with the axis ofthe work carrying arbor 4, and to prevent the tool from cutting into theblank as it travels across the same below the axis of arbor 4,-

the guide or formerBO is secured in the groove 29.. so that it projectsforwardly from the face of the plate 15. Moreover, it extends only halfway around the circumference of the groove. Consequently, when the toolhead is traveling around. the lower half of the groove it recedes fromthe blank and passes the same without destroying or marring thepreviously formed teeth or-the face thereof. Stops 53, 53 are adjustedso that when the tool has been fed forwardly to the required depth theclutch 49 is thrown and the direction of movement of carriage 11 isreversed to move it away from the work. As the carriage ap proaches itsrearward limit of movementthe (log 65 is withdrawn from socket 63 andthe work carrying arbor 4 indexed one space. 4

For a: purpose to be described means may also be provided for swingingor oscillating the work holding arbor, during the progress of thecut,'around an axis parallel with the arbor and passing through thetooth being out, although this is not essential and on certain classesofwork may be dispensed with. In the machine shown in the drawings thework carrying arbor 4 rotates in a'journal box which is slidable in anarc-shapedslot or guideway 81 in the arbor carriage 3 which is providedwith brackets -82 to which are pivotally connected arms or levers 83'having intermediate portions 84 embracing arbor 4, and at. their outerends connected to operating links 85, which are reciprocated up and downby oscillating levers 86 each controlled by a cam or eccentric 87 on thetransverse shaft 69.

While the machine shown may not be capable of cutting teeth ofmathematically correct cross section from end ,to end. the variationfrom the correct gear lines, especially on the larger sizes of gears, isso slight as to be ne, z;li,,;ible, and in fact disappears entirelyafter a few revolutions of the gears in actual use. On thejsmaller sizesof gears, however, it is found that the variation is material andbecomes greater asthe gear decreases in diameter. This is due to thefact that the amount of rise and fall of the cutting portion ofthe'tool, in passing across the face. of the gear, is fixed, for a givenpair or set of gears. In the case of the smaller gear the distance fromthe normal position of the tool to the work at the crest of the toothcurve is greater than in the case of a gear of larger diameter. In otherwords, the angular distance between the crest and end portions of atooth is greater in case of a small gearthan in the case of a largegear. The cutting tool therefore bears a different relation to the teethof a small gear from what it does to those of a large gear, unless acompea 1 :11:? movemen ciauuloved. The

nature and amount of variation of the tooth being cut from true toothlines, of course, depends largely on the relation between the radius ofswing of the tool to the radius. of the gear being cut, and also therelative positions of the axis of the work arbor and tool spindle. Insome cases the tooth being cut may at one point take the form shown bythe dotted lines a in Fig. 10, and at other points, or under othercircumstances, may take the form shownby dotted lines 6 in Fig. 11. Ineither case the proper cutting effect is obtained by swinging-the entiregear blank and the work arbor carrying the same around the point a as acenter. In the case illustrated in Fig. 10, the gear axis must beelevated to cause the tool to leave an addi tional small amount of metalat the apex of the tooth, as ate, and remove a small additional amountat its root, as at (i, while in the case of Fig. 11 the gear axis mustbe dropped to get the reverse effect.

The slot or guideway 81 is formed on the arc of a circle around thepoint no as a center and the cams or eccentrics 87 are so formed as toswing or oscillate the arbor 4 and the blank around the center w duringthe progress of the tool across the face of the blank, in accordancewith the known variation from the true mathematical cross section whichwould otherwise occur. It should also be understood that in case themechanism last described is used, means must also be provided formaintaining co operating relations between the indexing worm and wormgear. For this reason. the shaft 72 is journaled at its lower end in abracket 90 which swings around shaft 68 as an axis and carries bevelgears 73. At its upper end .said shaft 72 is journalcd in a bracket 91journaled onarbor 4. Vol-m T4 is splined or otherwise endwise movable onthe shaft 7 2. When the work arbor 4 swings upwardly the shaft 72 swingsaround shaft 68 as an axis and the worm H travels with the worm gear 75and bracket 91. and slides along its driving shaft 72 as an axis.

What I claim is:

1. The combination of a work holding arbor, a rotatable tool spindlehaving its axis transverse to the axis of said arbor, a cuttereccentrically mounted on said spindle, means for rotating said spindleto cause the cutter to travel across a cylindrical blank held on saidarbor, and means for oscillating said cutter about an axis parallel withthe axis of the arbor as. the tool travels across the blank.

2. The combination of a work holding arbor, a rotatable tool spindle.having its axis transverse to the axis of said arbor, a cuttereccentrically mounted on said spindle, means for rotating said spindleto cause the cutter to. travel across a cylindrical blank held on saidarbor, and means constructed and arranged to move said cutter toward andfrom the axis of the arbor while the cutter is moving across the blank,to thereby sew cure a cut of uniform radial depth from end to end.

3. The combination of a work holding arbor, a rotatable tool spindlehaving its axis transverse to the axis of said arbor, a cuttereccentrically mounted on said spindle, means for rotating said spindleto cause the cutter to travel across a cylindrical blank held on saidarbor, and a cam constructed and arranged to move said cutter toward andfrom the axis of the arbor as the cutter travels across the blank inaccordance with the position of the cutter longitudinally of theblank'axis, to thereby secure a cut of uniform depth from end to end.

4. The combination of a work holding arbor, a rotatable tool spindlehaving its axis transverse to the axis of said arbor, a movable cuttermounted on said spindle at one side of the axis thereof, means forrotating said spindle to cause the cutter to travel across a cylindricalblank held on said arbor, and means constructed and arranged to vary theposition of said cutter longitudinally of the spindle in accordance wi hthe curvature of the blank to thereby secure constant depth of out alongthe full line of cut across said blank.

5. The combination of a work holding arbor, a rotatable tool spindlehaving its axis transverse to the axis of said arbor, a cuttereccentrically mounted on said spindle and arranged to move in aplanepassing through the axis'thereof, means for rotating said spindle tocause the cutter to travel across a cylindrical blank held on saidarbor, and means for moving said cutter in saidplane toward and fromsaidspindle as the cutter travels across the blank, to thereby Sflgll'ea cut of uniform depth from end to en 6. The combination of a workholding arbor, a rotatable tool spindle having its axis transverse tothe axis of said arbor, a

cutter eccentrically mounted on said spindle and arranged to swing in aplane passing through the axis thereof, means for rotating said spindleto cause the cutter to travel across the blank at each rotation of saidspindle, and means for swinging the tool toward and from the blank as ittravels thereacross.

7. The combination of a work holding arbor, a rotatable tool spindlehaving its axis transverse to the axis of said arbor, a cuttereccentrically mounted on said spindle and arranged to swing in a planepassing through the axis thereof, means for rotating said spindle tocause the cutter to travel across the blank at each rotation of saidspindle, and a fixed former or guide for swinging said tool on saidspindle with reference to the blank as it travels across the same.

8. The combination of a Work holding arbor, a rotatable tool spindlehaving its axis transverse to the axis of said arbor, a tool holderpivoted on said spindle and carrying an eccentrically mounted cutterarranged to traverse the blank at each rotation of said spindle, meansfor rotating said spindle, a fixed former or guide, and means on saidtool holder arranged to contact said former or guide as the tool travelsacross the blank, and thereby adjust the tool with reference to theblank to secure a cut of uni-i form depth from end to end.

9. The combination of. a workholding arbor, a rotatable tool spindlehaving itsaxis transverseto the axis of said arbor, a cuttereccentrically mounted on said spindle, means for rotating said spindleto cause the cutter to travel across a cylindrical blankheld on saidarbor, said Work holding arbor being movable transversely With respectto-' theaxis of said tool spindle, and means for moving said arbortransversely as the cutter travels across the blank.

10. The combination of a Work holding arbor, a rotatable tool spindlehaving its axistransverse to the axis of said arbor, a

cutter eccentrically mounted on said spindle, 30

means for rotating said spindle to cause the cutter to travelv across acylindrical blank held on said arbor, and a cam operatively connected tosaid arbor and arranged to swing the blank around an axis passingthrough the tooth While the tool is crossing the blank.

In testimony whereof, I have hereunto set 1 my hand.

ISAAC E. MGCRACKEN.

Witnesses:

WILLIAM B. WHARToN, WM. P. LARKIN.

